1. Field of the Invention
This invention relates to a burner for burning a gaseous fuel which is low in combustion noise and high in combustion load and which has a relatively high thermal output, and, more particularly, to a burner of the type described which can have application in domestic combustion equipment.
2. Description of the Prior Art
A Bunsen burner is one type of burner of low combustion noise which burns a fuel-air mixture formed beforehand by mixing a fuel with a primary air in a flammable range. This type of burner has had wide application as domestic burner, because it is low in combustion noise and the preformed fuel-air mixture for combustion has a concentration which is in a flammable range and amenable to combustion. However, this type of burner has disadvantages in that it has a low combustion load and it is large in size.
Taking note of the fact that this type of burner is low in combustion noise, we have conducted research into high load combustion with this type of burner, and have discovered that the objects of reducing a noise and increasing a load during combustion can be accomplished by supplying secondary air in the form of a turbulent flow to an outer flame formed in a trailing portion of an inner flame which is in the form of a laminar flow. Based on this discovery, an invention has been developed which is disclosed in U.S. Ser. No. 771,912 filed on Feb. 25, 1977 (which corresponds to Japanese Laid-Open Patent Application No. 105335/77 dated Sept. 3, 1977). However, it has since been ascertained that this burner is not suitable for domestic use because combustion oscillation produced during combustion when the amount of heat produced by combustion reaches ten thousand odd kcal/h.